Manufacture of viscose thread



United States Patent MANUFACTURE OF VISCOSE THREAD Pieter Coenraad Limburg, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N.C., a corporation of Delaware No Drawing. Application April 25, 1955 Serial No. 503,786

Claims priority, application Netherlands May 12, 1954 6 Claims. (Cl. 18--54) The present invention relates to a viscose solution suitable for the manufacture of .viscose thread, and more particularly to the production of a high tenacity, highly fatigue resistant, viscose thread that is particularly adapted for use as a reinforcing material for cord tires, and for other industrial uses.

It is known from the Meyer Patent No. 1,877,933 to produce a delustered viscose yarn by adding, inter alia, quinoline to the viscose solution in sufficient quantities to form an emulsion with the viscose. The patentee also contemplated using an emulsifying agent to insure uni form distribution of the delustering agent in the viscose. The fact that the patentee used this type of compound to form an emulsion showed that he knew that quinoline is substantially insoluble in the viscose, because it is well recognized that any material that is soluble. therein has no effect on the luster. The range of quinoline used by the patentee was between 1% and 2% based on the viscose, and preferably 1.5%.

According to the present invention, it has been unexpectedly found that very minute amounts of quinoline can be used in the viscose for an entirely different purpose, namely, that of modifying the characteristics of the yarn produced from the viscose under certain particular conditions. Such small amounts, for example, about one-tenth or less of the amount used by the aforementioned patentee will dissolve as a true solution in the viscose, and therefore will not modify the luster. However, it will have a marked effect on the strength and fatigue resistance of the finished yarn, particularly when it is used in the so-called two-bath system, which embraces a coagulating bath containing ZnSO and a second hot aqueous solution in which the yarn is stretched to a high degree. These improved characteristics, together with the elongation in the wet and dry state, causes the yarn to be peculiarly adaptable for use as a reinforcing material in cord tires.

As in other known processes for modifying the Viscose characteristics, it has been determined that it is essential to use a substantial amount of zinc sulphate in the aqueous sulphuric acid coagulating bath, i.e., at least 2.5% zinc sulphate by weight. In fact, the yarn characteristics apparently improve by adding even more zinc sulphate, for example, in a range of 3%4.5% by weight.

It has been further determined that viscose can be used which contains 78% by weight of cellulose and 6% or slightly higher by weight of alkali. In a viscose of this composition, the quinoline content is preferably maintained between 0.075 and 0.15% based on the weight of the viscose. Such small quantities have been found to completely dissolve in the viscose; whereas when amounts are used exceeding 0.2% by weight based on the viscose, the solubility limit is reached and an emulsion starts to form, and incidentally, the spinning conditions become unsatisfactory. It is to be understood that the quinoline can be added during any of the viscose manufacturing steps, e.g., it can be added to the pulp or to the alkali solution or to the cellulose xanthate.

Patented Nov. 24, 1959 ICC borhood of 21% to 22.5%. In other words, if the zinc sulphate content is about 4% the sodium sulphate content should be about 18.5%. a a

In general, the temperature of the coagulating bath is maintained between 60 C. and C., and preferably about 70 C.; also, a relatively long thread immersion'is used in the coagulating bath, e.g. an immersion of at least 40 cm., and in fact favorable results have been obtained by using immersion distances up to 70 cm. and more depending upon the spinning velocity and the calculated filament denier duringthe immersion traject, e.g. with a filament denier of 3m the bath; optimum results were obtained when the thread remained in the bath for about 1 /2 seconds. After the threads have been formed in the coagulating bath, they can be stretched by means of godets and the like inany of the well known systems, and aftertreated either according to the continuous system or the discontinuous system. When the threads are to be used as. a reinforcing materialfor automobile tires or other industrial uses,-the stretching should be at least 70% and may take placein an air zone or in one or more .hot aqueous stretching baths. containing, if desirable, small amounts of sulphuric acid. Moreover, the threads may be slashed invany well known manner for further lowering the elongation.

The threads may be stretched in the gel state as. much as 20%-25% without any subsequent substantial loss in strength during cording and the wet strength, in general, is greater than 300 g./100 denier.

Additionally, other properties such as double loop strength, knot strength, resistance to abrasion, and resistance to fatigue are also very satisfactory, which make these products in the form of threads very suitable for their use as cords in automobile tires. Furthermore, staple fibers manufactured according to the process of the invention give an extremely resistant fiber yarn excelling in many respects the properties of cotton.

Example A viscose solution was made from cotton linter cellulose containing 7.7% by weight of cellulose, 5.5% by weight of alkali, and a quinoline content of 0.15% by weight. This solution having a ripeness of 17 according to Hottenroth was spun into a coagulating bath maintained at about 70 C. The immersion distance of the thread was 70 cm. The coagulating bath contained 6% by weight of sulphuric acid, 19% by weight of sodium sulphate and 3.5% by weight of zinc sulphate. The spinneret was made of gold and platinum and contained 1000 \orifices, each orifice having a diameter of 60 microns, which produced a thread having a high total denier suitable for use as a reinforcing material for tires.

The primary draw-off speed was 23.5 meters per minute, and between the primary draw-off rollers and the succeeding stretch roller having a peripheral speed of 44 meters per minute, the threads were stretched 87% in an aqueous bath containing 3% by weight of sulphuric acid maintained at a temperature of 90 C. The viscose pump was adjusted so that after the thread passed over the stretch roller it had a total denier of 1650. The thread was continuously aftertreated, dried and slashed.

The properties of the thread were as follows:

Dry strength 426 g./ 100 denier. Dry elongation 15.5% Wet strength 304 g./ 100 denier. Wet elongation 28.7%. Bone dry strength 510 g./100 denier. Bone dry elongation 11.1%

What is claimed is:

1. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improvement which comprises adding at most 0.2% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing at least 2.5% ZnSO, and withdrawing the thus formed thread from the bath and stretching the same at least 70%. i

2. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improvement which comprises adding 0.075%0.15% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing at least 2.5 ZnSO and withdrawing the thus formed thread from the bath and stretching the same at least 70%.

3. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improve ment which comprises adding 0.075 %-0.15% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing 3%-4.5% ZnSO, and withdrawing the thus formed thread from the bath and stretching the same at least 70%.

4. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improvement which comprises adding 0.075 %-0.15% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing 3%4.5% ZnSO and withdrawing the thus formed thread from the bath and stretching the same at least in a second hot aqueous acid bath.

5. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improvement which comprises adding 0.075%-0.15% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing 3%-4.5% ZnSO and a total salt content of 21%-22.5 and withdrawing the thus formed thread from the bath and stretching the same at least 70% in a second hot aqueous acid bath, 1 I

6. In the manufacture of high tenacity viscose thread and fibers in which a quinoline-containing viscose solution is spun into an acid coagulating bath, the improvement which comprises adding 0.075%-0.15% quinoline based on the weight of the viscose, to the viscose solution, extruding the viscose solution into an acid bath containing 3%-4.5% ZnSO 'and 12%20% Na SO and withdrawing the thus formed thread from the bath and stretching the same at least 70% in a second hot aqueous acid bath.

References Cited in the file of this patent UNITED STATES PATENTS Edwards ----a-- Jan. 15, 1957, 

1. IN THE MANUFACTURE OF HIGH TENACITY VISCOSE THREAD AND FIBERS IN WHICH A QUINOLINE-CONTAINING VISCOSE SOLUTION IS SPUN INTO AN ACID COAGULATING BATH, THE IMPROVEMENT WHICH COMPRISES ADDING AT MOST 0.2% QUINOLINE BASED ON THE WEIGHT OF THE VISCOSE, TO THE VISCOSE SOLUTION, EXTRUDING THE VISCOSE SOLUTION INTO AN ACID BATH CONTAINING AT LEAST 2.5% ZNSO4 AND WITHDRAWING THE THUS FORMED THREAD FROM THE BATH AND STRETCHING THE SAME AT LEAST 70%. 